//使用两个线程来累加 count 的值
public class Demo1 {
    //每个线程循环 1w 次，累加变量 count 的值，count 默认值为 0，注意线程安全问题。
    public static int count = 0;
    public static void main(String[] args) throws InterruptedException {
        Object o = new Object();
        Thread t1 = new Thread(() -> {
            for (int i = 0; i < 10000; i++) {
                synchronized(o){
                    count++;
                }
            }
        });
        Thread t2 = new Thread(() -> {
            for (int i = 0; i < 10000; i++) {
                synchronized(o){
                    count++;
                }
            }
        });

        t1.start();
        t2.start();

        t1.join();
        t2.join();
        System.out.println(count);
    }
}
